In cartilage, reactive oxygen species (ROS) signaling plays significant role in regulating chondrocyte proliferation, differentiation and maturation. To assure proper cellular function ROS is balanced by production of antioxidants;as unregulated ROS can cause dysfunction in gene expression, transcription factor signaling, and cell cycle. In aging, systemic disease, environmental toxin exposure, injury and inflammation, ROS production can overwhelm the antioxidant capacity triggering aberrant signaling leading to cell death, matrix degradation and pathological damage in both forming and permanent cartilages. Apoptosis signal-regulating kinase 1 (ASK1) a MAP kinase kinase kinase, is a well characterized protein implicated in pathological ROS signaling. In our preliminary data, we show Ask1 is present in growth plate and articular chondrocytes. We also show that hypoxia inducible factor 2 (HIF-2) is a transcriptional regulator controlling antioxidant expression in chondrocytes. Taken together, we propose that in cartilage the oxidative status of the cell is controlled by expression of HIF-2;and activation of Ask1 is a functional measurement of oxidative stress. We will investigate the relationship between HIF-2 controlled expression of antioxidants and activation of Ask1 by ROS. By manipulating the expression of these two molecules we will explore the normal and pathological role of ROS in chondrocyte differentiation and stasis.
In Specific Aim 1, using siRNA to silence Ask1 gene expression we will investigate the mechanism of action of Ask1 as an indicator of oxidative stress in chondrocytes and its role in ROS induced cartilage pathology.
In Specific Aim 2, we will investigate the expression of HIF-2 in controlling cellular oxidative status by antioxidant regulation. By manipulating the expression HIF-2, using siRNA to silence HIF-2 gene expression and a hypoxia independent plasmid for overexpression, we will determine cellular oxidative status, ROS mediated activation of Ask1, chondrocyte catabolic activity and survival. By carefully analyzing the signaling mechanisms altered by oxidative stress in chondrocytes, our proposed studies will have an enormous impact on understanding molecular mechanisms of oxidative stress, and provide important information for developing novel targets for therapeutic intervention. Public Health Relevance: This proposal will examine the relationship between environmental oxidants and antioxidant expression in cartilage cells;how this balance affects cartilage cell function and cartilage degeneration. Studies will include analysis of tissue and isolated cells from mice with impaired or improved antioxidant function and human osteoarthris tissue to determine these relationships. We will perform analyses to determine if genes that alter cartilage cell function are increased leading to the development of cartilage dysfunction.

Public Health Relevance

This proposal will examine the relationship between environmental oxidants and antioxidant expression in cartilage cells;how this balance affects cartilage cell function and cartilage degeneration. Studies will include analysis of tissue and isolated cells from mice with impaired or improved antioxidant function and human osteoarthris tissue to determine these relationships. We will perform analyses to determine if genes that alter cartilage cell function are increased leading to the development of cartilage dysfunction.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Small Research Grants (R03)
Project #
5R03DE020840-02
Application #
8120280
Study Section
NIDCR Special Grants Review Committee (DSR)
Program Officer
Wan, Jason
Project Start
2010-09-01
Project End
2013-08-31
Budget Start
2011-09-01
Budget End
2013-08-31
Support Year
2
Fiscal Year
2011
Total Cost
$115,875
Indirect Cost
Name
Thomas Jefferson University
Department
Orthopedics
Type
Schools of Medicine
DUNS #
053284659
City
Philadelphia
State
PA
Country
United States
Zip Code
19107
Steinbeck, Marla J; Eisenhauer, Peter T; Maltenfort, Mitchell G et al. (2016) Identifying Patient-Specific Pathology in Osteoarthritis Development Based on MicroCT Analysis of Subchondral Trabecular Bone. J Arthroplasty 31:269-77
Zhang, Qian-Shi; Eaton, Gregory J; Diallo, Carol et al. (2016) Stress-Induced Activation of Apoptosis Signal-Regulating Kinase 1 Promotes Osteoarthritis. J Cell Physiol 231:944-53
Chernets, Natalie; Zhang, Jun; Steinbeck, Marla J et al. (2015) Nonthermal atmospheric pressure plasma enhances mouse limb bud survival, growth, and elongation. Tissue Eng Part A 21:300-9
Eaton, G J; Zhang, Q-S; Diallo, C et al. (2014) Inhibition of apoptosis signal-regulating kinase 1 enhances endochondral bone formation by increasing chondrocyte survival. Cell Death Dis 5:e1522
Steinbeck, Marla J; Chernets, Natalie; Zhang, Jun et al. (2013) Skeletal cell differentiation is enhanced by atmospheric dielectric barrier discharge plasma treatment. PLoS One 8:e82143
Zhou, Jibin; Freeman, Theresa A; Ahmad, Firdos et al. (2013) GSK-3? is a central regulator of age-related pathologies in mice. J Clin Invest 123:1821-32
Freeman, Theresa A; Parvizi, Javad; Dela Valle, Craig J et al. (2010) Mast cells and hypoxia drive tissue metaplasia and heterotopic ossification in idiopathic arthrofibrosis after total knee arthroplasty. Fibrogenesis Tissue Repair 3:17